Could Immunotherapy Replace Antiretrovirals in HIV Treatment?
By Alex Keown
An experimental HIV immunotherapy treatment is showing significant promise in clinical testing. The two-drug combination is capable of suppressing HIV for months at a time, according to a study published by The Rockefeller University.
In clinical testing, the HIV drugs, called broadly neutralizing antibodies or bNAbs, were not only found to be safe, but “more effective than any previously tested antibody therapy,” the university announced. The goal of the study appears to be the development of a new HIV treatment that is not dependent on rigorous dosing. In its announcement, Rockefeller University said antiretroviral therapy has worked splendidly in making HIV a manageable condition. However, patient compliance continues to be an issue for a myriad of reasons. That inconsistency in the treatment regimen is a problem for some patients.
The bNAbs being studied in this new treatment, 3BNC117 and 10-1074, were discovered while researchers were studying individuals whose bodies have fought against HIV without the help of medications. Calling them “elite controllers,” Rockefeller said the “natural antibodies target proteins on the outside of the virus and recruit the body’s immune system to combat infection.” The goal of the study is to use the bNAbs to “turn anyone taking the medications into elite controllers,” the university said. That will allow the patients to suppress the virus “through an enhanced immune response.” An added benefit of the bNAbs, is they remain in the body longer than typical antiretroviral drugs, which means the medication should require less dosing.
The Rockefeller researchers said 3BNC117 and 10-1074 attack HIV from two different points. Because of that, the scientists speculated that combining the drugs might be a more effective treatment. Rockefeller noted that previous bNAb studies have shown that treatment with a single antibody has only yielded short-term effects.
This week the Phase Ib results were published by Rockefeller in Nature and Nature Medicine. Patients in the trial received three infusions of the combination bNAb treatment over the course of six weeks. According to the university, the treatment suppressed HIV for an average of 21 weeks among nine patients who “carried viruses that were sensitive to both antibodies.” Results showed that the individuals who received both bNAbs “did not develop resistance if their viruses were sensitive to the antibodies.” Additionally, the trial participants saw no major side effects. Researchers said the most significant reaction was mild fatigue.
While the experimental treatment could prove to be promising, the Rockefeller researchers said it has its limits. Not all forms of HIV respond to bNAbs. The researchers expressed optimism that bNAbs could be combined with other antibodies or antiretrovirals, then it could be more broadly used.
While the Rockefeller researchers move forward, last month the U.S. Food and Drug Administration (FDA) approved two new HIV-1 treatments developed by Merck. The FDA gave the go-ahead for Delstrigo, a once-per-day triple combination treatment, and Pifeltro, a new non-nucleoside reverse transcriptase inhibitor.
Data from CDC shows there were an estimated 37,600 new HIV infections in the United States in 2014, the most recent year for which the agency provides data. In February the FDA gave its approval to Gilead Sciences’ Biktarvy, a triple combination treatment of bictegravir and emtricitabine/tenofovir alafenamide for the treatment of HIV-1 in adults who haven’t been treated with antiretrovirals. In March, the FDA approved Trogarzo (ibalizumab), the first HIV-1 inhibitor for patients with multi-drug resistant HIV-1.